Mark Akselrod - Academia.edu (original) (raw)

Papers by Mark Akselrod

Radiotherapy and Oncology, 2014

Radiation Measurements, 2011

Fluorescent Nuclear Track Detectors (FNTD) and Optically Stimulated Luminescence Detectors (OSLD)... more Fluorescent Nuclear Track Detectors (FNTD) and Optically Stimulated Luminescence Detectors (OSLD) were investigated for application in proton therapy dosimetry. FNTDs and OSLDs are made of Al 2 O 3 :C,Mg single crystals and Al 2 O 3 :C powder, respectively. The detectors were irradiated in water, behind different thicknesses of plastic slabs and behind wedge shaped plastic absorbers. FNTDs positioned behind different thicknesses of plastic slabs and in water phantom show Bragg curves with a peak to entrance ratio of eight compared to about three from ionization chamber measurements. The over-response of FNTDs is attributed to the non-linear response of the power spectrum integral (PSI) parameter as a function of proton linear energy transfer (LET). The limitations of the wedge absorber experiment due to lateral proton straggling are discussed. Experimental data and image simulations were utilized to obtain LET dependencies for the FNTD power spectrum integral and fluorescence amplitude.

Radiation Measurements, 2011

This paper is a review of the latest progress in development of the next generation luminescent d... more This paper is a review of the latest progress in development of the next generation luminescent dosimetry technique-Fluorescent Nuclear Track Detectors (FNTD) that have important advantages in measuring fast neutrons and high energy heavy charge particles. New Mg-doped aluminum oxide crystals and novel imaging instrumentation for FNTD technology are discussed with regard to application in mixed neutron-gamma fields, medical dosimetry and radiobiological research. Dosimetric characteristics of new detectors are summarized.

Radiation Protection Dosimetry

ABSTRACT

International Symposium on Optical Memory and Optical Data Storage, 2005

ABSTRACT Optical and electronic processes during recording and readout in Al2O3:C,Mg fluorescent ... more ABSTRACT Optical and electronic processes during recording and readout in Al2O3:C,Mg fluorescent media are analyzed. Resonant two-photon absorption and high quantum yield of fluorescence permit utilization of modulated CW blue and red laser diodes.

Radiation Measurements, 2009

Properties of fluorescent nuclear track detectors (FNTDs) made of Al 2 O 3 :C, Mg crystals are in... more Properties of fluorescent nuclear track detectors (FNTDs) made of Al 2 O 3 :C, Mg crystals are investigated after irradiation in mono-energetic and broad spectrum neutron fields. Two types of neutron converters were investigated, high density polyethylene and natural LiF. Imaging in fluorescence contrast is performed using laser scanning confocal detection. Individual tracks induced by recoil protons, alpha particles and tritium ions are identified and counted. Two approaches to median neutron energy estimation using track density as a function of scanning depth and the ratio of track densities for two different converters are discussed.

Journal of radiation research, Jan 16, 2014

The geometric locations of ion traversals in mammalian cells constitute important information in ... more The geometric locations of ion traversals in mammalian cells constitute important information in the study of heavy ion-induced biological effect. Single ion traversal through a cellular nucleus produces complex and massive DNA damage at a nanometer level, leading to cell inactivation, mutations and transformation. We present a novel approach that uses a fluorescent nuclear track detector (FNTD) for the simultaneous detection of the geometrical images of ion traversals and DNA damage in single cells using confocal microscopy. HT1080 or HT1080-53BP1-GFP cells were cultured on the surface of a FNTD and exposed to 5.1-MeV/n neon ions. The positions of the ion traversals were obtained as fluorescent images of a FNTD. Localized DNA damage in cells was identified as fluorescent spots of γ-H2AX or 53BP1-GFP. These track images and images of damaged DNA were obtained in a short time using a confocal laser scanning microscope. The geometrical distribution of DNA damage indicated by fluoresce...

Radiation Measurements, 2014

2005 8th European Conference on Radiation and Its Effects on Components and Systems, 2005

... HCP. Aluminum oxide or sapphire is a chemically inert material and can beeasily sterilized by... more ... HCP. Aluminum oxide or sapphire is a chemically inert material and can beeasily sterilized by chemicals or heat. ... crystals. ER Benton's participation in this work was carried out under NASA Grant NAG8-01899. REFERENCES ...

Radiation Measurements, 2001

Al2O3 : C TL/OSL dosemeters were irradiated at di erent temperatures. TL sensitivity was found to... more Al2O3 : C TL/OSL dosemeters were irradiated at di erent temperatures. TL sensitivity was found to decrease by about 40% with decreasing irradiation temperature between +30 and −100 • C. High temperature TL peaks were shown to appear only if the irradiation temperature is higher than 200 • C. Recombination of holes with electrons in the dosimetric traps was proposed as a mechanism to explain these phenomena.

A new optical, non-destructive method of detecting and imaging individual heavy charged particle ... more A new optical, non-destructive method of detecting and imaging individual heavy charged particle tracks using fluorescent nuclear track detectors (FNTD) is investigated as a possible spectroscopic technology for heavy charged particles of low and high linear energy transfer (LET). The technique uses new luminescent aluminum oxide single crystals having aggregate oxygen vacancy defects and doped with Mg (Al 2 O 3 : C, Mg) in combination with laser scanning confocal fluorescence microscopy. Spectroscopic capabilities of this new method were demonstrated for energetic heavy ions of LET ∞ H 2 O ranging from 2.2 to 8767 keV/ m. The new technology is intended for use in neutron detection and dosimetry, proton and heavy ion radiobiology, and space radiation dosimetry as well as in nuclear and particle physics research.

Radiotherapy and Oncology, 2014

Radiation Measurements, 2011

Fluorescent Nuclear Track Detectors (FNTD) and Optically Stimulated Luminescence Detectors (OSLD)... more Fluorescent Nuclear Track Detectors (FNTD) and Optically Stimulated Luminescence Detectors (OSLD) were investigated for application in proton therapy dosimetry. FNTDs and OSLDs are made of Al 2 O 3 :C,Mg single crystals and Al 2 O 3 :C powder, respectively. The detectors were irradiated in water, behind different thicknesses of plastic slabs and behind wedge shaped plastic absorbers. FNTDs positioned behind different thicknesses of plastic slabs and in water phantom show Bragg curves with a peak to entrance ratio of eight compared to about three from ionization chamber measurements. The over-response of FNTDs is attributed to the non-linear response of the power spectrum integral (PSI) parameter as a function of proton linear energy transfer (LET). The limitations of the wedge absorber experiment due to lateral proton straggling are discussed. Experimental data and image simulations were utilized to obtain LET dependencies for the FNTD power spectrum integral and fluorescence amplitude.

Radiation Measurements, 2011

This paper is a review of the latest progress in development of the next generation luminescent d... more This paper is a review of the latest progress in development of the next generation luminescent dosimetry technique-Fluorescent Nuclear Track Detectors (FNTD) that have important advantages in measuring fast neutrons and high energy heavy charge particles. New Mg-doped aluminum oxide crystals and novel imaging instrumentation for FNTD technology are discussed with regard to application in mixed neutron-gamma fields, medical dosimetry and radiobiological research. Dosimetric characteristics of new detectors are summarized.

Radiation Protection Dosimetry

ABSTRACT

International Symposium on Optical Memory and Optical Data Storage, 2005

ABSTRACT Optical and electronic processes during recording and readout in Al2O3:C,Mg fluorescent ... more ABSTRACT Optical and electronic processes during recording and readout in Al2O3:C,Mg fluorescent media are analyzed. Resonant two-photon absorption and high quantum yield of fluorescence permit utilization of modulated CW blue and red laser diodes.

Radiation Measurements, 2009

Properties of fluorescent nuclear track detectors (FNTDs) made of Al 2 O 3 :C, Mg crystals are in... more Properties of fluorescent nuclear track detectors (FNTDs) made of Al 2 O 3 :C, Mg crystals are investigated after irradiation in mono-energetic and broad spectrum neutron fields. Two types of neutron converters were investigated, high density polyethylene and natural LiF. Imaging in fluorescence contrast is performed using laser scanning confocal detection. Individual tracks induced by recoil protons, alpha particles and tritium ions are identified and counted. Two approaches to median neutron energy estimation using track density as a function of scanning depth and the ratio of track densities for two different converters are discussed.

Journal of radiation research, Jan 16, 2014

The geometric locations of ion traversals in mammalian cells constitute important information in ... more The geometric locations of ion traversals in mammalian cells constitute important information in the study of heavy ion-induced biological effect. Single ion traversal through a cellular nucleus produces complex and massive DNA damage at a nanometer level, leading to cell inactivation, mutations and transformation. We present a novel approach that uses a fluorescent nuclear track detector (FNTD) for the simultaneous detection of the geometrical images of ion traversals and DNA damage in single cells using confocal microscopy. HT1080 or HT1080-53BP1-GFP cells were cultured on the surface of a FNTD and exposed to 5.1-MeV/n neon ions. The positions of the ion traversals were obtained as fluorescent images of a FNTD. Localized DNA damage in cells was identified as fluorescent spots of γ-H2AX or 53BP1-GFP. These track images and images of damaged DNA were obtained in a short time using a confocal laser scanning microscope. The geometrical distribution of DNA damage indicated by fluoresce...

Radiation Measurements, 2014

2005 8th European Conference on Radiation and Its Effects on Components and Systems, 2005

... HCP. Aluminum oxide or sapphire is a chemically inert material and can beeasily sterilized by... more ... HCP. Aluminum oxide or sapphire is a chemically inert material and can beeasily sterilized by chemicals or heat. ... crystals. ER Benton's participation in this work was carried out under NASA Grant NAG8-01899. REFERENCES ...

Radiation Measurements, 2001

Al2O3 : C TL/OSL dosemeters were irradiated at di erent temperatures. TL sensitivity was found to... more Al2O3 : C TL/OSL dosemeters were irradiated at di erent temperatures. TL sensitivity was found to decrease by about 40% with decreasing irradiation temperature between +30 and −100 • C. High temperature TL peaks were shown to appear only if the irradiation temperature is higher than 200 • C. Recombination of holes with electrons in the dosimetric traps was proposed as a mechanism to explain these phenomena.

A new optical, non-destructive method of detecting and imaging individual heavy charged particle ... more A new optical, non-destructive method of detecting and imaging individual heavy charged particle tracks using fluorescent nuclear track detectors (FNTD) is investigated as a possible spectroscopic technology for heavy charged particles of low and high linear energy transfer (LET). The technique uses new luminescent aluminum oxide single crystals having aggregate oxygen vacancy defects and doped with Mg (Al 2 O 3 : C, Mg) in combination with laser scanning confocal fluorescence microscopy. Spectroscopic capabilities of this new method were demonstrated for energetic heavy ions of LET ∞ H 2 O ranging from 2.2 to 8767 keV/ m. The new technology is intended for use in neutron detection and dosimetry, proton and heavy ion radiobiology, and space radiation dosimetry as well as in nuclear and particle physics research.